This invention relates to vehicle instrument displays.
Instrument clusters for vehicles are typically located on a vehicle dashboard and may include a speedometer, tachometer, engine condition indicator, ABS braking indicator, and other devices for monitoring vehicle operating conditions. The instrument cluster includes display marks that may have lighting to illuminate each mark. For example, the ABS braking mark may be illuminated when the vehicle is undergoing ABS braking. Typically, such lighting is provided by individual lamps that illuminate each indicator of the dashboard. However, individual lamps take up significant space and require a high voltage circuit to supply current to each of the lamps. The high voltage further requires insulation to protect against shock, thereby increasing the cost and size of the instrument cluster.
Recently, it has become more common to use optical light guides to direct illumination to each of the display marks of the instrument cluster. However, each mark requires its own light guide and light source so that each individual mark may be separately illuminated. A typical instrument cluster has many separate indicators that require such lighting. Each light guide associated with each indicator is painstakingly assembled into the cluster one at a time. Consequently, a great deal of time and effort is required to individually piece the light guides into the instrument cluster.
In addition, existing light guides for an instrument display such as a dial require the use of a dial appliqué. The dial appliqué is a film of plastic having instrument display marks, such as the hash marks of a speedometer gauge, the numbers for the gauge, vehicle telltales, and other marks. Most of the dial appliqué is opaque except for the illuminated portions. A light guide used with the dial appliqué, such as the light guide for the speedometer gauge, may illuminate large portions of the dial appliqué rather than just the marks. Accordingly, existing instrument displays waste lighting energy.
A need therefore exists for a thin instrument cluster that avoids the complexity, inefficiency, and size of existing lighting systems.